The present invention relates to a treatment method for preserving cut flowers.
Treatment methods for preserving cut flowers such as roses, to keep them appearing like natural flowers for a long period time for decoration are proposed, for example, in PCT International Publication No. WO91/03160 and U.S. Pat. No. 4,828,890, etc.
In the treatment methods disclosed in these documents, the water in the cellular structures of cut flowers, i.e., the tissue water is removed and substituted by permeating polyethylene glycol, with dyeing as required, and as shown in FIG. 5, cut flowers are treated generally through a dehydration process, permeation process and drying process in this order, to obtain cut flowers as products appearing like natural flowers.
The dehydration process is effected while the cut flowers are fixed in a container having a proper amount of a molecular sieve spread over its bottom and filled with a solvent having a specific gravity smaller than that of water, for example, an anhydrous organic solvent such as acetone.
In the dehydration process, the water in the tissue of cut flowers, i.e., tissue water is gradually dissolved into the solvent while the solvent migrates into the tissue. So, in the tissue of cut flowers, tissue water is removed and substituted by the solvent, while the mechanical structure of the tissue is maintained.
Then, the permeation process is effected while the cut flowers are fixed in a container filled with a permeating solution obtained by dissolving substitutive polyethylene glycol into acetone and a cellosolve. In this case, the polyethylene glycol used is a mixture consisting of polyethylene glycol compounds different in molecular weight suitable for the kind of cut flowers to be treated,
In this case, if the permeating solution contains a coloring matter such as a textile dye for acrylic fibers, the coloring matter permeates the tissue of cut flowers together with polyethylene glycol for dyeing them. That is, the permeation process and the dyeing process take place simultaneously.
After lapse of a certain time in the permeation process, the permeating solution is discharged, and the cut flowers are taken out and dried in the subsequent drying process, to obtain cut flowers as products.
The prior art has the following problems.
A. Dehydration Process
The prior art has the following problem in the dehydration process.
As described above, since the water dissolved into the solvent from the tissue of cut flowers in the dehydration process is larger in specific gravity than the solvent, the specific gravity of acetone tends to gradually rise due to the dissolved water.
While the molecular sieve remains new, most of the dissolved water is adsorbed by the molecular sieve. So, the dehydration by the solvent continues without causing the specific gravity of the solvent affected by the dissolved water to rise greatly.
However, if the total amount of dissolved water exceeds the water adsorbability of the molecular sieve with the progression of the dehydration process, the water remaining without being adsorbed raises the specific gravity of the solvent sharply, to quickly deprive the solvent of its adsorbability.
Since the prior art does not monitor the change of dehydratability, the dehydration process may be continued to waste time even though the dehydratability of the solvent is lost. Thus, efficient dehydration is difficult.
B. Drying Process
The prior art has the following problem since the cut flowers delivered from the permeation process are dried into products without being washed.
Since the acetone and cellosolve in the permeating solution are volatile, they are diffused into air in the drying process, but polyethylene glycol as a high molecular material remains deposited on the outside surfaces of petals.
The polyethylene glycol remaining deposited on the outside surfaces of petals like this absorbs water in air if the humidity is higher than a certain level, and becomes sticky to touch. So, the phenomenon remarkably lowers the commercial value of cut flowers.
C. Dyeing Process
In the prior art, depending on the kinds of cut flowers, uneven dyeing can happen without allowing even dyeing, to remarkably lower the commercial value of cut flowers.
The inventor intensively experimentally studied and found that the uneven dyeing is caused because the permeation of the permeating solution into the cellular structures of petals occurs differently from portion to portion in the petals.
In the prior art, the water in the cellular structures is substituted by an anhydrous organic solvent such as acetone in the dehydration process, and the solvent is substituted by the permeating solution containing polyethylene glycol in the permeation process. In this case, the substitution rate is different from cellular structure to cellular structure.
Therefore, after lapse of a certain time in the permeation process, the solvent is filly substituted by the permeating solution in the cellular structures higher in substitution rate, to dye the cellular structures by the coloring matter contained in the solvent, but in the cellular structures lower in substitution rate, the solvent is less substituted by the permeating solution, to keep the color remaining diluted.
D. Permeating Solution, etc.
In the prior art, when the cut flowers to be treated include plural colors and are intended to be treated simultaneously, permeating solutions as many as the number of colors are necessary since each permeating solution contains one coloring matter for each color of flowers, and they occupy a vast space.
Furthermore, if the permeating solution for any disused color is dumped, such problems as waste treatment and resource wastage arise because of the organic solvent contained, and if the permeating solution is stored as contained in a container, it needs an extra storage space.
An object of the present invention is to solve the problem described in the above A, and the object can be achieved by a treatment method for preserving cut flowers, which has a dehydration process for removing the tissue water of cut flowers using a solvent, and a permeation process for letting polyethylene glycol permeate after dehydration, to substitute the solvent by polyethylene glycol, characterized in that the dehydration process is effected while cut flowers are fixed in a container having a proper amount of a molecular sieve spread over its bottom and filled with a solvent having a specific gravity smaller than that of water, wherein the specific gravity of the solvent is measured to monitor the dehydratability with the progression of dehydration, for detecting the time for exchanging the molecular sieve.
According to this method, the change in the dehydratability of the solvent can be monitored by measuring the specific gravity of the solvent, and the time when the specific gravity sharply rises is detected as the time for exchanging the molecular sieve for a new one, to restore the dehydratability of the solvent, thereby allowing the solvent to be continuously used and allowing the dehydration process to be continued without waste of time.
The molecular sieve removed from the container for exchange can be dried for re-use.
Another object of the present invention is to solve the problem described in the above B, and the object can be achieved by a treatment method for preserving cut flowers, which has a dehydration process for removing the tissue water of cut flowers using a solvent, and a permeation process for letting polyethylene glycol permeate after dehydration, to substitute the solvent by polyethylene glycol, characterized in that the permeation process is effected by a solution obtained by dissolving polyethylene glycol into a solvent, wherein a washing process for washing the cut flowers containing polyethylene glycol as a substitute of tissue water by a solvent not containing polyethylene glycol is added.
According to this method, the polyethylene glycol remaining deposited on the outside surfaces of petals after the permeation process can be washed away by a solvent, and the stickiness otherwise caused after the drying process can be prevented by removing the extra polyethylene glycol deposited on the outside surfaces of petals.
A further other object of the present invention is to solve the problem described in the above C, and the object can be achieved by adding a coloring matter for dyeing to the permeating solution used in the permeation process and also to the dehydrating solvent used in the dehydration process in the above method.
According to this method, a coloring matter is contained in the solvent occupying the cellular structures as a substitute of tissue water as achieved in the dehydration process. So, when a coloring matter is added for dyeing in the permeation process, even the portions of petals low in the rate of substituting the solvent by the permeating solution have the same coloring matter concentration, and uneven dyeing can be avoided.
A still further other object of the present invention is to solve the problem described in the above D, and the object can be achieved by having a decoloration process for letting the permeating solution, dehydrating solution or washing solution respectively containing a coloring matter pass through a column packed with a decoloring agent, so that the permeating solution, dehydrating solution or washing solution delivered from the decoloration process may be re-used.
According to the above method, since the permeating solution, dehydrating solvent or washing solvent respectively containing a coloring matter for dyeing can be re-used after decoloration, it is not necessary to dump the permeating solution, dehydrating solvent or washing solvent of any disused color. So, such problems as waste treatment and resource wastage do not arise, and the storage space for them is not required.
In the present invention, the cut flowers to be treated for preservation also include leaves and stems.